Method of manufacturing a bipolar transistor having thin base region

Abstract

A method of manufacturing a semiconductor device includes a monocrystalline semiconductor layer of one conductivity type with a first insulating film covering the semiconductor layer. An aperture is selectively formed in the first insulating film to expose a part of the semiconductor layer. A first polycrystalline semiconductor film of an opposite conductivity type is formed on the first insulating film and has an overhang portion projecting over the aperture from an edge of the first insulating film defining the aperture. A second polycrystalline semiconductor film and a monocrystalline semiconductor film of the opposite conductivity type are grown simultaneously on a bottom surface of the overhang portion of the first polycrystalline semiconductor film and on the part of the monocrystalline semiconductor layer respectively until monocrystalline semiconductor film is in contact with the second polycrystalline semiconductor film, with a second insulating film selectively formed on the monocrystalline semiconductor film with leaving a part thereof to be exposed.